To meet a reliability requirement and a power requirement of a load, in a power supply system, a number of power supply modules are often used in parallel by using a distributed system. During parallel use, as power supply modules differ, a current share on each module may differ from one another, leading to difference in current stress and thermal stress on each module, thereby reducing system reliability. To ensure equal currents (uniform current distribution) on multiple power supply modules in the system as well as uniform distribution of the current stress and thermal stress, current equalization has to be supported for power supply modules in parallel connection.
At present, a switching power supply is experiencing a transition from one with analog control to one with digital control. A digital power supply is efficient and has a high power density. Along with the notion of energy conservation, an efficient digital power supply wins increasing popularity in users. However, in an existing power supply system, complete replacement of any analog power supply by a digital power supply is yet to be achieved. That is, both digital and analog power supplies will be inserted and used in parallel in an existing power supply system. To ensure system and module reliability, current equalization has to be supported too in case both digital and analog power supplies are inserted, which poses a challenge.
At present, most modes of automatic current equalization control are based on analog-to-analog control or digital-to-digital control. There is a major difference in current equalization for analog power supplies and for digital power supplies. With such differentiated designs, either analog current equalization is adopted, in which case no current equalization can be performed on an inserted digital power supply; or digital current equalization is adopted, in which case no current equalization can be performed on an inserted analog power supply. Thus, no effective current equalization can be implemented in case both digital and analog power supplies are inserted in one power supply system. There is an existing challenge of implementing current equalization in case both digital and analog power supplies are inserted in one power supply system, so as to ensure reliability of a power supply module and of the entire power supply system.
With differentiated designs for digital current equalization and for analog current equalization in related art, no solution has been proposed for implementing effective current equalization in case both digital and analog power supplies are inserted in one power supply system.